Smokebox structure



P 1945- LE ROY THOMPSON 2,398,058

SMOKE BOX STRUCTURE I Filed May 17, 1945 2 Sheets-Sheet 1 id Z7ATTORNEYS p 1946. LE ROY THOMPSON 7 2,398,058

SMOKE BOX STRUCTURE Filed May 17, 1945 2 Sheets-Sheet 2 Fi 6 r0 /7 99a/&z 7 30a ATTORNEYS motive to any considerable extent.

Patented Apr. 9, 1946 UNITED STATES PATENT OFFICE SMOKEBOX STRUCTURE LeRoy Thompson, Blakely, Ga., assignor to L- comotive EconomizerCorporation, New York, N. Y., a corporation of Delaware Application May17, 1945, Serial No. 594,349

4 Claims. (0!. 230--97) smoke stack and the steam issuing from thenozzle under a pressure determined in part by the size of the nozzle,creates the draft which draw the gases through the boiler tubes from thecombustion chamber. The present invention is concerned, moreparticularly, with a novel smoke box structure which includes means fordistributing the action of the draft over the entire group of boilertubes, so that the draft is more nearly equalized throughout the tubes,with the result that a lower draft than is ordinarily required may beemployed and firing conditions and steam generation are improved. Thesmoke box structure of the invention is also so constructed thatincandescent cinders entrained by and carried along with the gases arethrown out of the gas stream and are also broken up so that such cindersare quickly consumed and little or none of them in live condition passout of the stack.

In my prior Patent 2,104,958, of January 11, 1938, and in my co-pendingapplication, Serial No. 536,465, filed May 20, 1944, patented September4, 1945, No. 2,384,407, I have disclosed smoke box structures Whichprevent live cinders from being carried out of the stack of a loco- Inboth structures referred to, partition means are provided within thesmoke box for directing the gases of combustion forwardly through thesmoke box from the front ends of the boiler tubes in two streams and thepartition means define a space within which the nozzle and the lower endof the stack lie in alignment 2. short distance apart. In order to enterthat space, the burned gases must change direction sharply and passbetween louver plates arranged in banks. As a result of such change ofdirection, some of the cinders are thrown out of the streams of gas andthe remainder impinge upon the louver plates at such velocity as to bedisintegrated, so that incandescent cinders are broken up into fineparticles which are quickly consumed.

The partition means of the structures of the patent and applicationinclude a pair of vertical side walls extending lengthwise of the smokebox on either side of the longitudinal axis thereof,

and a curved rear wall which connects the rear ends of the side wall andlies with its convex face opposed to the front end wall of the boilerthrough which the fire tubes open. This curved wall subdivides the gasesissuing from the tubes into the two streams which flow forwardly throughthe smoke box along the 'outer faces of the side walls to the banks oflouvers, between which the gases pas into the space between the sidewalls. The exhaust nozzle and the lower intake end of thestack liewithin the space referred to and, in order to afford the gases properaccess to the stack as Well as to provide suitable passages for theforward travel of the gases, the side walls must be properly spaced fromone another and from the inner walls of the smoke box and the curvedrear wall must be properly spaced from the lower end of the stack. 7 Y

In the installation of the partition means disclosed in the patent andthe application in the smoke boxes of locomotives of variou types,differing with respect to the diameter of the smoke box and the distancebetween the center of the smoke tack and the front end sheet of theboiler, I have discovered that the curved rear wall of the partitionmeans may function, if properly shaped and located, as a means forequalizin the draft over the entire group of tubes. As is well known, inan ordinary locomotive the draft exercises its greatest pull through thecentrally located tubes of the boiler, so that the middle of the fire inthe combustion chamber burns better than that along the side walls ofthe chamber, and the greatest heat transfer is through the walls of thecentral tubes. However, if the curved wall of the partition means is ofproper form and placed in proper relation to the front ends of thetubes, the wall acts in the nature of a baflle and distributes thedraft, so that all of the boiler tubes conduct more nearly equalquantities of gases. A a result, the side tubes take a greater part inthe recovery of heat from the gases, combustion conditions are improved,and the draft may be reduced without reduction in steam production.Reduction in the draft reduces the velocity of the gases of combustionthrough the tubes and smoke box, and this in turn reduces cinder cuttingdamage and the quantity of cinders entrained and carried along by thegases. Also reduction in the draft permits the use of a larger exhaustnozzle, which creates less back pressure on the cylinders and increasesthe efficiency of the locomotive.

The present invention is, accordingly, directed to the provision of anovel locomotive smoke box to the stack and effecting disintegration ofsuch cinders as continue to be carried on by the gases.

For a better understanding of the invention, reference may be made tothe accompanying drawings, in which: V

Fig. 1 is a longitudinal section through-a locomotive smoke boxstructure embodying the invention on the line I--I of Fig.2;

Fig. 2 is a sectional view on the line -2-2"o Fig. l; and

' Figs. 1 B-and 4--are views similar to Fig. 2 showing modifiedconstructions.

-In the construction shown in Fig.1; the locomotive boiler -I isillustrated as including-afront 'wall I I and fire tubes- I2 whichopenthrough the front wall. -'I'helocomotiveis equipped withasuperheater -includinga dry pipe I3 through which steam from theboilerfiows through a manifold I4 to tubes I 5 whi chextendinto certain ofthe-boiler tubes. The-steam returns to another passage-in the m'anifoldand flows therefrom through a pairof-steampipes lfi-to the cylinders.

The smoke box I'I--is-mounted at the front of the boiler as an extensionof the boiler shell; and parts of the superheater including the manifoldand tubes I5 and lfi-liewithin the smoke box. A smoke'stack I8 extendsinto the smoke box through the upper wall-thereof and terminates abovethe top of an exhaust nozzle I9- which receives spent steam from thecylinders. The front wall of the smoke box-is provided with a door 2|through which access may be had to the interior of the box.

The smoke 'box illustrated is providedwith partition meansgenerallydesignatedfl and similar in construction to that disclosed inmy co-pending Patent 2,384,407. Thepartition means include a pair ofside walls 23 lying on: opposite sides ofthe longitudinal axis ofthe-smoke box and rising vertically'from the bottom of the smoke box.Walls 23extend to the front wall 20 of the smoke box and are cut awayintheir lower for- -ward corners to provide openings 24. A top plate 25rests 'on the upper ends of thewalls and extends across the interlor ofthe smoke box from one'side to the other, the stack I8 extending throughan opening in the top wall. The opposite" ends of the top wall areplates 26, 21 which close the ends of the spacein the smoke box abovethe top plate.

The rear ends of the side walls- 23 areconnected'by a vertical curvedwall 28- which has 'a curvature about'a centerin the'longitudinal axisof the smoke box. The gases issuing from-the tubes I2 are divided by thecurved wall and flow forwardly in two streamsthrough passages 29,30'along the outer sides'of wall'23, the passages being defined by thosewalls, the top plate '25, and

the smoke'box shell. The'gases then enter the chamber defined by thesidewalls 23, the curved:

rear wall 28, the bottomof the smoke-box; and the topplate 25. Inentering this chamber; the gases abruptly change direction, and theypass into the spaceeither through banks' 3 I' and 32 of I louver platesmounted vertically in the opposite side walls adjacent the stack, orthrough of the entire-group of tubes.

' apart.

banks of louver plates 33 which are mounted to extend between the sidewalls around the edges of openings 24,

The spacing of walls 23 varies in smoke boxes of different dimensions,and the cross-sectional areas of passages 29 and 30 vary accordingly.

The steam pipes I6 extend-downwardlythrough thepassageszand for propertravelgof the gases through the passages, it is desirable that the totalfree cross-sectional area of the passages at the steam pipes be within65% to 95% of the total "area of tubes I2.

'1 have foundthat the curved rear wall of the front ends of. the tubesand of proper radius, may act to equalize the draft over the front endsIn locomotives of ordinary construction, the draft produced by theaction of the exhaust steam discharging from nozzle'I9 intothelower endof the stack-I8 is 'strongeston the central 5. tubes with the resultthat' these tubes conductthe greater portion of the gasesandthe-greaterpart oi the heat transfer. -Also, the central part of thefire burns best. By properly constructing the curved rear wall'28,

the -central-tubes =of -the--boiler maybe baffled somewhat so that thedraft is more-nearlyuniform-throughout the entire group of tubes. Thisimproves firing conditions and heat transfer through the-tube walls withresultant improvement in steam generation.

With the action of the draft equalized,..as .explained, a lower dra'ftmaybe-employed than would otherwisebe required-and this.affordsinumerous advantages. 1Thus,.a larger steam home may beemployed, with consequent reduction in the back pressure on thecylinders and improved operating efficiency. Also, the .gases travelingthrough-the tubesand smoke box move at a lower speed, and this reducescindercutting. Also, the amount of i cinders entrained by the. gases andcarried-along withthem andthe prevention of the'discharge ofincandescent cinders from the smoke a stack is facilitated. When thegases change direction in'-flowing from passages 29, 30

into theinterior of the chamber Within side walls 22, a considerableproportion of. the cinders carried along by thegases are thrown-out ofthe stream. Manyof the remaining cinders are caused to impinge upon thelouver plates in the banks 32,. 33, and the-cinders are therebydisintegrated so that. those that are incandescent can be quicklyconsumed. With lowered draft and lower velocity of the gases, theincandescent cinders-are carried along more slowly and a longer time isafforded for'their consumption.

In order that the 'rear wall 28 may be effective as a baflle toequalizethe draft, it must lie at a particularspacing 'Withf reference to thefront wall of the boiler and must have'aradius of curvature 'whichvaries "with its spacing from that front wall. a In the specificinstallation illustrated in Figs. 1 and 2; the diameter of the smoke boxis 88 inches and th'ewalls- 23 are 40 inches The free areas of'passages29, 30 at the steam. pipes I6 total about 1400=square inches, Whichisabout of the-total-area of the boiler tubes I2; and thus lieswithin thelimits previously given. The radius of curvature of the wall 28 is 20inches, that is,-ha1f the distance between walls 23; and the wall 28lies 29-inches away from the 'frontwall I I "of the boilenwith themeasureto be satisfactory, in that the distance between the curved wall28 and the front wall of the boiler and the radius of curvature of wall28 are appropriate to cause that wan to equalize the draft over thetubes l2.

In installations in which the smoke box is of smaller diameter than thatin the construction shown in Fig. 1, side walls 23 must lie closertogether in order that the passages 29, 30 may have a totalcross-sectional area at the steam pipes which bears the proper relationto the total area of the boiler tubes. With the side walls lying closertogether, the wall 28, if drawn on a radius equal to half the distancebetween the side walls and located at the same distance from the frontwall I l as in the specific example above set forth, would have a lesseffect in distributing the draft because its radius of curvature is lessthan that of the curved wall in the example. In such an installation,therefore, wall 28 should lie closer to the front wall of the boilerthan in the specific example, but it frequently happens that parts ofthe superheater lying within the smoke box prevent wall 28 from beinplaced as close to wall H as is necessary to obtain the desired effect.When this situation is encountered, the effectiveness of wall 28 fordistributing the draft may be increased by increasin its radius ofcurvature, and an installation in which that expedient is resorted to isillustrated in Fig. 3.

In the installation of Fig. 3, the smoke box diameter is approximately82 inches, and the distance between Walls 23 is 42 inches. The totalfree cross-sectional areas of passages 29a and 30a at the steam pipesIlia is approximately 1090 5 square inches, which is about 81% of thetotal cross-sectional area of the boiler tubes I211. The closestpermissible spacing between walls 28a and lla measured along thelongitudinal axis of the boiler is a little more than 36 inches, and thecurved wall may not be placed nearer to wall Ila because of thesuperheater installation. To increase the effectiveness of wall 28a inequalizing the draft, the radius of curvature of the wall is made 26inches, or 5 inches greater than half the distance between walls 23a andthe ends of the wall 28a thus extend outwardly beyond the Walls 23a. Bythus increasing the radius of curvature of wall 28a, its draftequalizing effect is increased and the same results are obtained as inthe Fig. 2 construction.

In some installations, such as that shown in Fig. 4, the smoke stack l8blies relatively far to the rear of the smoke box. The curved wall 28bmust lie a few inches away from the lower end of the smoke box in orderto provide adequate space for the gases traveling through the spacebetween walls 23b to the stack. In such a construction, the rear wall281) may be so close to the front wall I lb of the boiler that it wouldhave too great a baffling effect, if formed with a radius of curvatureequal to one-half the maximum distance between walls 23b. In such aninstallation, the radius of curvature of wall 281) is made less thanone-half the maximum distance between walls 231) and the ends of thecurved wall are connected to divergent walls 34 which lead to the endsof parallel portions of walls 231).

In the specific installation shown in Fig. 4, the smoke box has adiameter of 77 inches and the distance between the parallel portions ofwalls 222) is 37 inches. The passages 29b and 38b have a total freecross-sectional area at the steam pipes of 1065 square inches, which isapproximately 85% of the total cross-sectional area of the tubes l2b.,The distance between walls I lb and 28b is'about 25% inches, and thisspace is determined by the location of the stack which lies far backfromthe. front of the smoke box. With the spacing from walls llb and 28breferred to, wall 281) may not be formed on a radius of'curvature equalto 18 inches, that is, one-half the distance between the parallelportions of wall 22b, because a wall 281) of such curvature at so closea spacing to the wall I lb would have too great a baflling efiect.Accordingly, in the Fig. 4 installation, the necessity of placing wall28b so close to wall llb in order that the gases may have adequateaccess to the lower end of the stack, requires that wall 282). be.formed on a radius substantially smaller than one-half the distancebetween the parallel portions of walls 28b, and in the actualinstallation, the radius of curvature of Wall 2817 is 15 inches.

It will be apparent from the foregoing that the curved wall 28 at therear of the partition means must be formed with a radius of curvaturewhich varies with different installations. In all locomotives, thespacing of walls 22 0f the partition means depends on the diameter ofthe smoke box, because the walls must be at such a distance from oneanother as to provide gas passages 29, 36 which have a total freecross-sectional area at the steam pipes equal to a value lying betweenparticular percentages of the total crosssectional areas of the boilertubes l2. If the superheater does not prevent, the wall 28 may be formedwith a curvature on a radius equal to onehalf the distance between walls22 and be placed at such a distance from the front wall of the boiler asto effect equalization of the draft. However, in some installations, thepresence of the superheater requires that the curved wall 28 be at sogreat a distance from the front wall of the boiler that if the curvedwall were formed on a radius equal to one-half the distance betweenwalls 22, the curved wall would not provide the desired draft equalizingaction. Accordingly, in such an installation, the draft equalizingeffect of the curved wall must be increased, and this i have too great abaffling effect and the central tubes of the boiler would not be aseffective as the fire tubes. In such an installation, the radius onwhich the curved wall is drawn is less than one-half the distancebetween the side walls 22.

As indicated above, locomotive smoke boxes vary greatly in diameter andin the location of the stack therein. Also, the proportion of a smokebox occupied by superheater parts varies somewhat, and the draft variesdepending on the boiler pressure and the size of the exhaust nozzle.Because of these and other factors, it is not possible to lay down ageneral rule for the construction of the partition means. However, Ihave found that the curved rear wall of the partition means may beeffectively employed for equalizing the draft throughout the boilertubes, provided the wall is formed on a radius of curvature which variesfrom a value less than one-half the distance between the side Walls ofthe partition means to a value greater than one-half that distance, inaccordance with the distance of the curved wall from the front wall ofthe boiler. The distance between the side walls of the partition meansvaries in accordance with the diameter of the smoke box and with thetotal crosssectional area of the boiler tubes, as above set forth.

In the new smoke box structure, the use of a curved rear wall serving toequalize the draft also appears to reduce turbulence in the gas streamsflowing forwardly through passages 29, 30. Because of the draftequalization provided by a curved wall of proper formation and location,I have found that the draftmay be substantially reduced and a largerexhaust nozzle employed. This results in numerous. advantages above setforth.

I claim:

1. In a locomotive including a boiler containing fire tubes openingthrough a front wall of the boiler, a smoke box attached to the frontend of the boiler and receiving gases of combustion from the tubes, asmoke stack extending into the smoke box from above with its lower endabove the bottom of the smoke box, and an exhaust nozzle projectingupwardly from the bottom of the smoke box in alignment with the stack,the end of the nozzle being spaced from the lower end of the stack, thecombination of partition means within the smoke box cooperating with thewalls thereof to define a pair of gas passages extending forwardly alongthe sides of the smoke box past the axis of the stack and also defininga chamber within which lie the nozzle and the lower end of the stack,the passages communicating with the chamber through openings in thepartition means, and a vertical wall forming the rear end of thepartition means and directing the gases from the tubes into thepassages, the vertical wall lying sufficiently close to the front wallof the boiler to act as a baffle with respect to the central tubes ofthe boiler, said vertical wall having a curvature substantially that ofthe arc of a circle about a center in the longitudinal axis of the smokebox and drawn on a radius varying from less than half the maximumtransverse dimension of the chamber to greater than half said dimensionin accordance with the distance along said axis of the smoke box fromsaid vertical Wall to the front end wall of the boiler.

2. In a. locomotive including a boiler containing fire tubes openingthrough a front wall of the boiler, a smoke box attached to the frontend of the boiler and receiving gases of combustion from the tubes, asmoke stack extending into the smoke box from above with its lower endabove the bottom of the smoke box, and an exhaust nozzle projectingupwardly from the bottom of the smoke box in alignment with the stack,the end of the nozzle being spaced from the lower end of the stack, thcombination of partition means within the smoke box cooperating with thewalls thereof to define a pair of gas passages extending forwardly alongthe sides of the smoke box past the axis of the stack and also defininga chamber within which lie the nozzle and the lower end of the stack,the passages communicating with the chamber through openings in thepartition means, and having a total free cross-sectional area varyingbetween approximately 65% and of the total cross-sectional area of theboiler tubes, and a vertical wall forming the rear end of the partitionmeans and directing the ases from the tubes into the passages, the wallhaving a curvature substantially that of the arc of a circle about acenter in the longitudinal axis of the smoke box and drawn on a radiusvarying from less than half the maximum transverse dimension of thechamber to greater than half said dimension in accordance with thedistance along the axis of the smoke box from said curved wall to thefront end wall of the boiler.

3. In a locomotive including a boiler containing fire tubes openingthrough a front wall of the boiler, a smoke box attached to the frontend of the boiler and receiving gases of combustion from the tubes, asmoke stack extending into the smoke box from above with its lower endabove the bottom of the smoke box, and an exhaust nozzle projectingupwardly from the bottom of the smoke box in alignment with the stack,the end of the nozzle being spaced from the lower end of the stack, thecombination of partition means within the smoke box cooperating with thewalls thereof to define a pair of gas passages extending forwardly alongthe sides of the smoke box past the axis of the stack and also defininga chamber within which lie the nozzle and the lower end of the stack,the passages communicating with the chamber through openings in thepartition means, and a vertical wall forming the rear end of thepartition means and directing the gases from the tubes into thepassages, said vertical wall being curved and having end portionsprojecting into said passages, the vertical wall lying sufficientlyclose to the front wall of the boiler as to act as a baffle with respectto the central tubes of the boiler efiective for substantiallyequalizing the draft on said tubes.

4. In a locomotive including a boiler containing fire tubes openingthrough a front wall of the boiler, a smoke box attached to the frontend of the boiler and receiving gases from the tubes, a smoke stackextending into the smoke box from above with its lower end above thebottom of the smoke box, an exhaust nozzle projecting upwardly from thebottom of the smoke box in alignment with the stack and spaced from thelower end thereof, and steam pipes leading downwardly within the smokebox at the sides thereof to the cylinders, the combination of partitionmeans within the smoke box cooperating with the walls thereof to definea pair of gas passages having a total free cross-sectional area at thesteam pipes varying between approximately 65% and 95% of the totalcross-sectional area of the boiler tubes, the partition means defining achamber between the passages in communication therewith, the lower endof the stack and the nozzle lying within the chamber, and a verticalwall forming the rear end of the partition means and directing the gasesfrom the tubes into the passages, the wall being curved and lyingsufficiently close to the front wall of the boiler as to act as a bafflewith respect to the central tubes of the boiler effective forsubstantiall equalizing the draft on said tubes.

LE ROY THOMPSON.

